Table 3. Standardized neuropsychological composites for PD and non-PD peers with mean, standard deviation, and minimum/maximum scores shown.

	PD (n = 40)	Non-PD (n = 40)	t	p-value
Attention	0.31± 0.69, -1.39/2.12	0.38±0.73, -1.39/1.51	0.40	0.69
P. Speed	-0.48±0.61, -1.76/0.83	0.16±0.47, -0.58/1.27	5.25	<0.001*
W. Memory	0.34±0.51, -0.59/1.77	0.87±0.57, -0.45/1.92	4.42	<0.001*
Inhibition	0.07±0.68, -1.25/1.60	0.21/0.69, -1.10/1.45	1.12	0.27
Reasoning	0.43±0.84, -0.93/2.52	0.78/0.50, -0.36/1.76	2.28	0.03
Language	0.28±0.71, -1.17/1.73	0.55±0.67, -0.63/2.30	1.77	0.08
Visual	0.15±0.83, -2.50/1.34	0.50±0.59, -0.64/1.59	2.91	0.03
Memory	0.75±0.77, -0.67/2.33	1.15±0.55, 0.11/2.11	2.67	0.01
Motor	-0.57±1.12, -2.50/1.85	-0.47±0.67, -1.80/1.25	0.48	0.63

W. Memory = Working Memory; P. Speed = Processing Speed;

*Significant after Bonferroni correction. See S1 Table for the composite subtest raw and standardized scores by group.

Note: Further examination of the motor speed scores showed that group motor tapping scores were normally distributed (skewness; PD = 0.493; non-PD = 0.029), but different in range. For PD: although fifteen of the participants (38%) scored within the below average to impaired range, 10% (4 / 40) scored in the superior range. These superior scores associated with lower LED metrics (three had LED < 400; one of 700) and a disease range of 3 to 8 years. By contrast, for the non-PD peers 10% (4/40) scored in the below average with none in the superior range. Removing the four individuals with PD who had superior finger tapping scores showed a trend for finger tapping difference (t(73) = 1.78, p = .079; PD mean = -0.79).